Slip-ring arrangement with integrated rotary swivel joint for liquids

ABSTRACT

An arrangement for the transfer of electric current, a liquid medium and a gaseous medium between fixed and rotatable sections. A protective casing surrounds sliding brushes pressing against sliding surfaces. A passage for each medium is parallel with rotation and arranged at a boundary surface between the fixed and rotating sections. Passage transfer pipes in both sections communicate with the passages. A collector chamber arranged in the fixed section and an outlet pipe lead the gaseous medium out of the tubular rotating section. The arrangement for the transfer of a liquid medium is coaxially arranged inside the arrangement for the transfer of electric current. The protective casing provides a collector chamber for the gaseous medium.

A This invention relates to an arrangement for the transfer of electriccurrent, a liquid medium and a gaseous medium between a section in afixed position and a section rotating in relation thereto, i.e. a sortof a slip-ring arrangement, the arrangement for the transfer of electriccurrent comprising sliding surfaces supported by the rotating sectionand sliding brushes supported by the fixed section and arranged to pressagainst the sliding surfaces, and a protective casing surrounding them,the arrangement for the transfer of a liquid medium comprising for eachmedium circuit a passage parallel with the rotation and arranged at theboundary surface between the fixed section and the rotating section,with which passage transfer pipes in both sections communicate and whichis sealed in the axial direction of the rotating section with sealsarranged on both sides of the passage, and the arrangement for thetransfer of a gaseous medium comprising a collector chamber arranged inthe fixed section and at least one outlet pipe connected to said chamberfor leading the gaseous medium out of the rotating section, which hasbeen given a tubular form.

An arrangement described above may have to be utilized for instance whendifferent kind of equipment is hung on a rotating, vertical tubularshaft via which electric current, lubricating oil, cooling air etc. hasto be fed to said equipment. Such a situation may arise e.g. inconnection with a propeller drive arrangement described in CanadianPatent 1,311,657. In this arrangement the motor of a ship is arranged ina cylindrical chamber, which is secured pivotably to the body of theship by means of a tubular shaft. Electric current to the electric motorarranged in said chamber is fed via said tubular shaft. Likewisenecessary hydraulic fluids, lubricating oils and possible other liquids,such as bilge water, also have to be fed via said rotating tubularshaft. In addition, the motor may have to be cooled with coolant air,also via said tubular shaft.

If it is desired to construct the tubular shaft freely rotating or atleast to allow the tubular shaft a relatively wide range of rotation,the different feeding arrangements needed have to be constructed bymeans of the arrangements described in the preamble. A problem in thatcase is the large space required by the different feeding arrangementsin the axial direction of the tubular shaft. Such a considerable lengthis problematic for two reasons. Firstly, the space available inside thebody of a ship is limited and the length of the necessary arrangementsshould thus be as small as possible. Secondly, the considerable lengthof the arrangements above the supporting point of the tubular shaftcauses to the tubular shaft itself torsional forces that are difficultto control. For instance the slip-rings and the cabling necessary forthe feeding arrangements for electricity easily weigh several hundredsof kilos when the power required by the motor is of the order ofmegawatts.

It is the object of the present invention to provide an arrangement fortransmitting electric current, a liquid medium and a gaseous mediumbetween a section fixed in its position and a section rotating inrelation thereto so that the space occupied by this arrangement may beminimized especially in the axial direction of the rotating section.This is achieved with the arrangement of the invention, which ischaracterized in that the arrangement for the transfer of a liquidmedium is coaxially arranged inside the arrangement for the transfer ofelectric current and that the protective casing of the arrangement forthe transfer of electric current is essentially gas, tight and providesa collector chamber for the gaseous medium.

In the arrangement of the invention electric current, a liquid mediumand a gaseous medium may thus be transmitted via a space the axiallyrequired space of which corresponds in practice with the space requiredby the arrangement for the transfer of electric current.

The cross section of the protective casing of the arrangement for thetransfer of electric current is preferably a polygon and an outlet pipefor the gaseous medium is arranged to replace one or more sides of theprotective casing. By means of this procedure the direction of theexhaust air pipe may easily be chosen appropriate and on the other handthe volume flow needed may easily be achieved by taking into use anadequate number of the sides of the protective casing.

If the angle of rotation of the rotating section is not limited, boththe sliding surfaces of the arrangement for the transfer of electriccurrent and the passages of the arrangement for the transfer of a liquidmedium, arranged in the rotating direction, are annular. By means ofsuch sliding rings and, on the other hand, annular passages the rotationmay be completely free and an alternating motion is not even necessaryfor the extreme positions to be reached.

On the other hand, the total length of the arrangement of the inventionmay be further shortened if the angle of rotation of the rotatingsection is limited between ±90° or less. If in fact in this case thesliding surfaces of the arrangement for the transfer of electric currentare arranged in the shape of a semi-circle or possibly even shortersectors, two or even more transfer connections may be placed in the sameheight position. Naturally, the same procedure may also be applied tothe arrangement for the transfer of a liquid medium, but the need forthis is practically quite small because of the narrowness of thepassages of the liquid medium. In addition, the passages of thearrangement for the transfer of a liquid medium would have to beprocessed by milling instead of using lathe work, which would complicateproduction.

Furthermore, it is preferable that, in addition to the passagesconnected to the medium circuits, the arrangement for the transfer of aliquid medium comprises a passage arranged below these passages andprovided with a transfer tube on the side of the fixed section only foruse in detecting possible leakages in the passages connected to themedium circuits. By means of such an extra passage, possible leaks inthe medium circuits are easily detected and, at least equallyimportantly, media are prevented from leaking inside the tubular shaft.

In the following the arrangement of the invention will be described ingreater detail with reference to the accompanying drawing, in which

FIG. 1 is a side view and a partial section of the arrangement of theinvention and

FIG. 2 is a top view and a partial section of the arrangement accordingto FIG. 1.

FIG. 1 is a side view and a partial section of the arrangement of theinvention. Reference numeral 1 denotes a section in a fixed position ofthe arrangement. Reference numeral 2 denotes a section rotating relativeto the fixed section 1, the former being thus connected to e.g. thetubular shaft of the propeller drive arrangement described in CanadianPatent 1,311,657.

In the arrangement according to FIGS. 1 and 2, the arrangement for thetransfer of electric current comprises sliding brushes 4 connected tothe fixed section 1, via which brushes electric current can be fed intothe rotating section. As is evident from FIG. 1, the sliding brushes 4are arranged at a plurality of different levels, in order that thenecessary electric current can be fed into the electric devices arrangedin the rotating section. The arrangement described in FIG. 1 may beapplied to feeding an electric motor equipped with two triphase statorwindings. Slip-rings 3 whereto appropriate transfer cables 11 areconnected are connected to the arrangement for feeding electric currentto the rotating section 2. In practice the space in the vertical axialdirection needed by the arrangement for feeding electric current isrelatively large as the slip-rings have to be placed at a relativelylong distance from one another to avoid spark-over.

In the arrangement of FIGS. 1 and 2 the rotating section is realizedfreely rotating, and thus the slip-rings 3 are completely annular. Ifthe angle of rotation is limited e.g. to the value ±80°, one slip-ringcould be divided into two sectors of at most 180° and thus two electricfeeding connections could be constructed at the same level.

The arrangement for the transfer of a liquid medium, which forms onepart of the arrangement of the invention, comprises, per each mediumcircuit, an annular passage 6, arranged in the direction of the rotationat the boundary surface between a fixed section 1' and the rotatingsection 2, with which passage transfer pipes, arranged in the axialdirection of the rotating section in both sections 1' and 2,communicate. The transfer pipe connected to the rotating section 2 isdenoted by reference numeral 8. A transfer pipe connected to the fixedsection 1' and functioning as a part of one of the medium circuits isnot shown in the Figure, but such a pipe would correspond to a transfertube 7 shown in the Figure, the purpose of which will be describedbelow. The annular passages 6 are sealed with seals 9, arranged in theaxial direction of the rotating section on both sides of the passage. Inthe relation described above, the arrangement for the transfer of aliquid medium, such as water and oil, is conventional per se. Inaccordance with the invention the procedure differs from theconventional in that the arrangement for the transfer of a liquid mediumis coaxially arranged inside the arrangement for the transfer ofelectrical current. In this way the space required by them in the axialdirection corresponds in practice to the axial length of the arrangementfor the transfer of electric current.

The arrangement for the transfer of a liquid medium comprises, inaddition to the passages 6 connected to the medium circuits, a passage16, arranged below these passages and equipped with a transfer pipe 7only on the side of the fixed section 1', for use in detecting possibleleakages in the passages 6 connected to the medium circuits. As thepassage 16 is located below the other passages 6 and as it is not underpressure unlike the other passages 6, possible liquid leaking from theother passages 6 is gathered into the passage 16. This prevents theliquids from leaking downward and also their access into free air space,where they could vaporize. As stated above and as can be seen in FIG. 1,the transfer pipe 7 connected to the passage 16 rises upward above thearrangement for the transfer of a liquid medium. As the liquids in thepassages 6 are under pressure, the level of the liquid in the pipe 7rises under the influence of this pressure, and may easily be detectedby means of a suitable probe.

As is evident from FIG. 1, the transfer pipe 8 for the liquid medium isconnected to the rotating section whereas the transfer pipe 7 isconnected to the fixed section 1', the latter forming thus in practicean annular fixed section between two rotating sections. This is based onthe fact that a shaft 12, rotating with the rotating section 2, isarranged at the axial middle line of the arrangement, inside of whichshaft are arranged optical and electrical cables. These optical cablestransmit especially different measuring information from the equipmentarrange in the rotating section. The messages received in the fixedsection from these optical cables are transferred by a separate opticalslip-ring package 13, arranged in a space 14 above a protective casing 5designed for the arrangement for the transfer of electric current. Asregards this optical transfer arrangement the arrangement shown in FIG.1 does not differ from the conventional.

As has become evident above, the equipment inside the tubular shaft andthe cylindrical equipment space connected thereto have to be cooled withcoolant air. This coolant air is fed into the equipment via separatepassages, situated at different levels, in practice lower than thearrangements described in FIGS. 1 and 2, and they have not been shown inthe Figures for clarity. These passages are conventional per se. Removalof the gaseous medium, i.e. in practice most often the coolant air, is,however, realized differently from the conventional in the arrangementof the invention. In this arrangement the protective casing 5, arrangedaround the feeding arrangement for electric current, is utilized. As isevident especially from FIG. 2, the cross section of the protectivecasing 5 is arranged in the shape of a polygon. Additionally, theprotective casing is gas tight to a degree that it may be used as acollector chamber for the coolant air to be removed. Thus the hot airdischarged from the tubular shaft may be led to an outlet passagereplacing one of the side walls of the protective casing 5. This outletpassage is denoted by the reference numeral 10 in FIG. 1. In FIG. 1 aheat exchanger 15 has been additionally connected to the outlet passage,from which heat exchanger the coolant air is thus removed relativelycool. By the use of a protective casing, which is in any case needed inconnection with the arrangement for feeding electric current, as acollector chamber, the structure of the equipment may be essentiallysimplified and its total length may be essentially shortened in theaxial direction of the rotating section.

The arrangement of the invention has been explained in the above only inprinciple and by way of one exemplifying embodiment. It is thus evidentthat the arrangement of the invention may be realized by means ofmechanical structures that differ considerably from the ones described,without, however, departing from the protective scope of the appendedclaims. The idea of the invention is to decrease the axial length neededby different feeding arrangements by realizing the collection of thecoolant air to be removed by means of a protective casing of the feedingarrangement for electric current and additionally by placing the feedingarrangement for the liquid medium coaxially inside the feedingarrangement for electric current.

We claim:
 1. Arrangement for the transfer of electric current, a liquidmedium and a gaseous medium each having a medium circuit between asection in a fixed position and a section rotating in relation thereto,the arrangement for the transfer of electric current comprising slidingsurfaces supported by the rotating section and sliding brushes supportedby the fixed section and arranged to press against the sliding surfaces,and a protective casing surrounding them, the arrangement for thetransfer of a liquid medium comprising for each medium circuit a passageparallel with the rotation and arranged at a boundary surface betweenthe fixed section and the rotating section, with which passage transferpipes in both sections communicate and which is sealed in the axialdirection of the rotating section with seals arranged on both sides ofthe passage, and the arrangement for the transfer of a gaseous mediumcomprising a collector chamber arranged in the fixed section and atleast one outlet pipe connected to said chamber for leading the gaseousmedium out of the rotating section, which has been given a tubular form,wherein the arrangement for the transfer of a liquid medium is coaxiallyarranged inside the arrangement for the transfer of electric current andthe protective casing of the arrangement for the transfer of electriccurrent provides a collector chamber for the gaseous medium. 2.Arrangement as claimed in claim 1, wherein the cross section of theprotective casing (5) of the arrangement for the transfer of electriccurrent is a polygon and that said, at least one outlet pipe (10) forthe gaseous medium is arranged to replace one or more sides of theprotective casing.
 3. Arrangement as claimed in claim 1, wherein theangle of rotation of the rotating section (2) is not limited, whereinboth the sliding surfaces (3) of the arrangement for the transfer ofelectric current and the passages (6) of the arrangement for thetransfer of a liquid medium, arranged in the rotating direction, areannular.
 4. Arrangement as claimed in claim 1, wherein the angle ofrotation of the rotating section is at most ±80°, wherein the slidingsurfaces of the arrangement for the transfer of electric current cover asector of at most 180° of the periphery of the rotating section. 5.Arrangement as claimed in claim 1 wherein the arrangement for thetransfer of a liquid medium comprises, in addition to the passages (6)connected to the medium circuits, a passage (16), arranged below thesepassages and equipped with a transfer pipe (7) only on the side of thefixed section (1'), for use in detecting possible leakages in thepassages (6) connected to the medium circuits.
 6. An arrangement for thetransfer of electric current, a liquid medium and a gaseous medium eachhaving a corresponding medium circuit between a fixed section and atubular section rotatable relative to the fixed sectioncomprising:slidable surfaces supported by the rotatable section andslidable brushes supported by the fixed section said brushes arranged topress against the slidable surfaces and a protective casing surroundingthe brushes and slidable surfaces, the arrangement for the transfer ofthe liquid medium and gaseous medium each including a passage for eachmedium circuit parallel with a direction of rotation of the rotatablesection and arranged at a boundary surface formed between the fixedsection and the rotatable section; passage transfer pipes in each of thesections communicating with each passage, and seals for sealing thepassages in an axial direction arranged on both sides of the passages;and the arrangement for the transfer of a gaseous medium including afirst collector chamber arranged in the fixed section and at least oneoutlet pipe connected to said chamber for leading the gaseous medium outof the rotatable section, the arrangement for the transfer of the liquidmedium being coaxially arranged inside the arrangement for the transferof electric current, and further including a passage arranged below thepassages for the medium circuits and equipped with a transfer pipe onlyon the side of the fixed section for detecting leaks in the passagesconnected to the medium circuits and the protective casing of thearrangement for the transfer of electric current providing a secondcollector chamber for the gaseous medium.